Wednesday, February 8, 2012

Crank Arm Length

I bought my Cervelo P3 in 2010. It was my first time trial bike. The bike shop fit the bike to me, and that's the fit I've been riding ever since.

I've definitely learned, adjusted and changed in the two years since that original fitting, so I decided to look into getting re-fit on the bike. I know I can be more aero, and I know I'm not getting as much power out of the pedals as I would like. I've split 5:20 in two Ironman races now, which equates to a 21 mile-per-hour average speed. That's pretty good, until you figure that there are guys in the race averaging 23, 25, even 27 miles-per-hour! I'm obviously doing something wrong.

Anyway, Vitaly and Michael G. both recommended I talk to the guy who fit them on their bikes, so I reached out to him. We had a long chat on the phone a few days ago, and it only took that short conversation for him to convince me that my crankset is too big for me. I did some poking around online and everything I read only confirmed that hypothesis. Someone who's 5'7" should not be riding on cranks that are the same length as a guy who's 6'7"!

Now I'm on a quest to find a crankset that's smaller. Andrew (the fitter) suggests I buy a used crankset and have it machined down to 155mm or so - a 17.5mm drop from where I am now. Yikes! The other option's picking up a stock 165mm crankset and just being happy with a 7.5mm change.

In either case, the shorter cranks should allow me to raise my seat, improve my hip-angle and lower my handlebars. And because the crank arms are shorter, my legs won't come up as high toward my chest, which should make things a bit more comfortable. This all sounds good to me: smaller cranks mean higher cadence, smoother pedal-stroke, improved aerodynamics and a more comfortable ride.

Now all I've got to do is figure out how I'm going to get there, and pull the trigger on a large lump of metal or two.